Composition

ABSTRACT

2,2,4,4,6,6-hexamitroadamantane and a method of making the same.

GOVERNMENTAL INTEREST

The Government has rights in this invention pursuant to Contract NumberD21-89-C-0013 awarded by the U.S. Army. The invention described hereinwas made under a contract with the Government and may be used andlicensed by or for the Government for Governmental purposes without thepayment to us of any royalties.

FIELD OF USE

2,2,4,4,6,6-Hexanitroadamantane and method of making the same. Thiscomposition is useful in an energetic composition or material such aspyrotechnics and explosives.

BACKGROUND OF THE INVENTION

Polynitropolycyclic cage molecules are central to the current effortsaimed at energetic materials to meet modern requirements for fuels,propellants and explosives. (Alster, J; Iyer, S; Sandus, O. in "TheChemistry and Physics of Energetic Materials", Bulusu S. ed., Kluwer,"The Netherlands", p. 641.) These systems are particularly attractivebecause strain energy incorporated in the cage combined with theaccumulation of nitro groups tend to bolster energy output, while themolecular compactness produces high density materials favorablyincreasing the detonation velocity. For a recent review of the chemistryof polynitropolycyclic cage molecules, see Marchand, A. P. "Tetrahedron"1988, 44,2347. Simultaneously, high crystal density materials areadvantageous in volume-limited applications.

As a class of compounds, polynitroadamantanes have been of interest formore than a decade since Sollott and Gilbert first synthesized anddemonstrated that the bridgehead-substituted1,3,5,7-tetranitroadamantane exhibited very low impact sensitivity.Please see Sollott, G. P.; Gilbert, E. E. "J. Org Chem" 1980, 45,5405.Subsequently, several members of this class of compounds have beenreported including 2,2-dinitro- and 2,2,6,6-tetranitroadamantane.(Archibald, T. G.; Baum, K. "J. Org Chem", 1988, 53,4645)

SUMMARY OF THE INVENTION

2,2,4,4,6,6-Hexanitroadamantane, 1, was prepared by the sequence ofreactions outlined in scheme 1. ##STR1##

This synthetic strategy overcomes problems associated with stericcrowding and takes advantage of the ease with which an oxime can beconverted to the geminal dinitro function by oxidative nitration with98% nitric acid.

The starting material for this synthesis was4-methyleneadamantane-2,6-dione, 2, available by the treatment ofbicyclo-[3.3.1]-nonane-2,6-dione (See Schaefer, J. P.; Honig, L. M. "J.Org. Chem" 1968, 33, 2655 and references therern.) with acetic anhydrideand sulfuric acid. (McCabe, P. H.; Nelson, D. R.; Routledge, W."Tetrahedron", 1977, 1749.) The carbonyl groups were Protected asethylene ketals and the exocyclic methylene unit was ozonated to yield2,2,6,6-bis(ethylenedioxy)adamantan-4-one, 4. Compound 4 is ideallysuited for the synthesis of 1 as rt allows for sequential conversion ofcarbonyl groups that bear a 1,3, relationship as shown to be necessaryin the synthesis of 2,2,4,4-tetranitroadamantane. (Dave, P. R.; Ferraro,M.; Ammon, H. L.; Choi, C. S. "J. Org. Chem 1990, 55, 4459.) It shouldbe noted that the corresponding bis(methylketal) has been reported(Snatzke, G.; Klein, H. "Chem. Ber." 1972, 105, 244.) Compound 4 wasconverted to the corresponding oxime 5, which was treated with 98%nitric acid in refluxing methylene chloride. The reaction mixture afterworkup showed the presence of ethylene ketal by NMR and so was treatedwith conc. sulfuric acid rn methylene chloride to affect deketalization.The resulting mixture was purified by chromatography to afford4,4-dinitroadamantane-2,6-dione 6 ;n 37% yield. Treatment of 6 withhydroxylamine hydrochloride in refluxing methanol gave the correspondingbis(oxime) 7. Treatment of 7 with 98% nitric acid in refluxing methylenechloride gave, after work-up and chromatography,2,2,4,4,6,6-hexanitroadamantane (21%) and4,4,6,6-tetranitroadamantan-2-one (34%). A small amount of 6 was alsorecovered.

Thus, the synthesis of the conformationally-rigid polynitropolycyliccage molecule, 2,2,4,4,6,6-hexanitroadamantane, 1, and its precursors,4,4,6,6-tetranitroadamantan-2-one, 8 and4,4-dinitroadamantane-2,6-dione, 6 has been achieved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following section describes specific experimental procedures usedfor the synthesis.

2,2,6,6-bis(Ethylenedioxy)-4-methyleneadamantane, 3. A mixture of 2 (1g, 5.7 mmol), ethylene glycol (1.4 g, 22.6 mmol) and P-Toluene SulfonicAcid (0.1 g) in benzene was heated at reflux in a flask fitted with adean stark tube for 4 hours. The reaction mixture was then cooled toroom temperature and concentrated in vacuo. The residue was partitionedbetween water (100 mL) and methylene chloride (100 mL), and the layerswere separated. The organic layer was washed with saturated sodiumbicarbonate solution (100 mL), dried (MgSO₄), filtered and the filtratewas concentrated under reduced pressure. The residue was recrystallizedfrom hexanes to give 3 as a colorless microcrystalline solid (1.3 g,87%), mp 119°-20° C.:IR (KBr) 1650 cm¹ (m); ¹ H NMR (CDCl₃) δ 1.78-2.08(m, 8H), 2.39 (bs, 2H), 3.92-4.04 (m, 8H), 4.75 (s, 2 H).

2,2,6,6-bis(Ethylenedioxy)adamantan-4-one, 4. Ozone was bubbled througha solution of 3 (0.35 g, 1.32 mmol) in ethyl acetate (50 mL) at -78° C.until the blue color of ozone persisted. The mixture was allowed to warmto room temperature and dimethyl sulfide (5 mL) was added and stirredfor 30 min. The reaction mixture was then concentrated in vacuo and theresidue was chromatographed on silica gel, eluting with a 1:4 mixture ofacetone/hexanes to give 4 (0.15 g, 41%), mp 154°-6° C. (fromacetone/hexane):IR (KBr) 1720 cm⁻¹ (s); ¹ H NMR (CDCl₃) δ 1.85-2.12 (m,2H), 2.55 (m, 2H), 3.9-4.12 (m, 8H).

2,2,6,6-bis(Ethylenedioxy)-4-oximidoadamantane, 5. To a suspension of 4(1 g, 3.75 mmol) in absolute ethanol were added sodium acetatetrihydrate (3.2 g, 23.5 mmol) and hydroxylamine hydrochloride (0.8 g,11.5 mmol). The resulting mixture was stirred overnight at roomtemperature. The reaction mixture was then concentrated in vacuo and theresidue was partitioned between methylene chloride (100 mL) and water(100 mL). The layers were separated and the organic layer was washedsuccessively with saturated sodium bicarbonate solution and brine, dride(MgSO₄), filtered and the filtrate was concentrated under reducedpressure. The residue was recrystallized from methylene chloride/hexanesmixed solvent system to give 5 (0.9 g, 86%), mp 219°-21° C.: IR (KBr)3260 (br, s), 1670 cm⁻¹ (w).

4,4-Dinitroadamantan-2,6-dione, 6. To a refluxing solution of 5 (0.9 g,3.2 mmol) in methylene chloride (50 mL) under nitrogen was added dropwise a solution of 98% nitric acid (20 mL), urea (0.15 g, 250 mmol) andammonium nitrate (0.15 g, 200 mmol) in methylene chlorine (20 mL).(CAUTION: 98% nitric acid should be handled carefully. Urea and ammoniumnitrate should be added carefully in small portions to the nitricacid/methylene chloride solution since a slight exotherm occurs andnitrogen oxide fumes are evolved). A blue-green color appeared initiallywhich faded as more nitric acid was added. After the addition wascompleted, the mixture was heated under reflux for a further 30 min. Thereaction mixture was then cooled to room temperature and poured over ice(50 g). After the ice had melted the layers were separated and theorganic layer was washed successively with saturated sodium bicarbonatesolution (100 mL) and brine (100 mL), dried (MgSO₄), filtered and thefiltrate was concentrated in vacuo. The residual oil was dissolved inmethylene chloride (50 mL) and conc. sulfuric acid (10 mL) was added.The mixture was stirred for 3 hours at room temperature and then waspoured into 100 g of ice water mixture. The layers were separated andthe organic layer was washed with saturated sodium bicarbonate solution(100 mL) followed by brine (100 mL). The organic phase was dried(MgSO₄), filtered and the filtrate was concentrated under reducedpressure to yield a solid residue that was recrystallized fromacetone/hexane mixed solvent system to give pure 6 as a colorlessmicrocrystalline solid (0.3 g, 37%), mp 244°-46° C.: IR (KBr) 1740 (s),1560 cm⁻¹ (s); ¹ H NMR (CD₃ COCD₃) δ 2.04-2.18 (m, 2H), 2.42-2.58 (m,4H), 2.80 (m, 2H), 3.82 (m, 2H).

4,4-Dinitro-2,6-dioximidoadamantane, 7. To a suspension of 6 (0.3 g,1.18 mmol) in methanol 100 mL) were added sodium acetate trihydrate (2.4g, 17.65 mmol) and hydroxylamine hydrochloride (0.6 g, 9.30 mmol). Theresulting mixture was heated under reflux for 4 hours and then stirredat room temperature overnight. The reaction mixture was thenconcentrated in vacuo. The residue was partitioned between methylenechloride (100 mL) and water (100 mL). The layers were separated and theorganic layer was washed successively with saturated sodium bicarbonatesolution (50 mL) and brine (50 mL). The organic phase was dried overMgSO₄, filtered and the filtrate was concentrated under reduced pressureto yield 7 (0.25 g, 76%) mp 208°-10° C. (methylene chloride/hexanes): IR(KBr) 3240 (br, s), 1660 (w), 1580 (s), 1360 cm⁻¹ (m).

2,2,4,4,6,6-Hexanitroadamantane, 1, and4,4,6,6-Tetranitroadamantan-2-one, 8. To a refluxing solution of 7 (0.1g, 0.35 mmol) in methylene chloride (25 mL) under nitrogen was addeddropwise a solution of 98% nitric acid (20 mL), urea (0.15 g, 250 mmol)and ammonium nitrate (0.15 g, 200 mmol in methylene chloride (20 mL).Initially a blue-green color appeared which faded as more nitric acidwas added. After the addition was completed the mixture was furtherheated under reflux for 30 min. the reaction mixture was then cooled toroom temperature and poured onto ice (50 g). After the ice had meltedthe layers were separated and the organic phase was washed successivelywith saturated sodium bicarbonate solution (50 mL) and brine (50 mL).The methylene chloride solution was dried (MgSO₄), filtered and thefiltrate was concentrated in vacuo. The residue was chromatographed oversilica gel using an acetone/hexane mixed solvent gradient elution(starting with 5% acetone to 30% acetone in hexane). The first fractionafforded 1 (0.03 g, 21%) as a colorless microcrystalline solid, mp198°-200° C. (acetone/hexanes): IR (KBr) 1580 cm⁻¹ (s); ¹ H NMR (CDCl₃)δ 2.1-2.4 (m, 2H), 2.65-3.15 (m, 4H), 3.35-3.54 (m, 2H), 4.76-4.80 (m,2H).

Continued elution gave 8 as a colorless solid (0.04 g, 34%), mp 24°-41°C. (acetone/hexanes): IR (KBr) 1740 (s), 1580 cm⁻¹ (s); ¹ H NMR (CDCl₃)δ 2.0-3.08, (m, 7H), 4.76-4.80 (m, 2H).

Continued elution gave 8 as a colorless solid (0.04 g, 34%), mp 240°-41°C. (acetone/hexanes): IR (KBr) 1740 (s), 1580 cm⁻¹ (s); ¹ H NMR (CDCl₃)δ (2.0-3.08, (m, 7H), 3.45-3.54 (m, 1H), 4.05-4.06 (m, 1H), 4.83-4.83(m, 1H).

What is claimed is:
 1. 2,2,4,4,6,6-Hexanitroadamantane.